Hemophilia A Research Program (HARP): A Novel Study Design for a Multicenter and Decentralized Prospective Observational Longitudinal Cohort Study in Hemophilia A

Background: Hemophilia A is a rare X-linked bleeding disorder caused by factor VIII (FVIII) deficiency. There is a compelling need in hemophilia to better understand the causes of bleeding in females and the factors underlying FVIII inhibitor development. To meet this need we are establishing a new NHLBI funded Hemophilia A Analytical Cohort Research Program (HARP) as part of a public-private partnership to support an Intergenerational Precision Medicine Program for the study of factor VIII (FVIII) immunogenicity in severe hemophilia A (Harpf8.org).

The HARP objectives are: 1) Longitudinal assessment of bleeding in females with a severe hemophilia A genotype beginning in pregnancy; 2) Longitudinal assessment of anti-FVIII antibody formation in severe hemophilia A from birth through at least the first 2 years of life; 3) Studies of causes of bleeding in females with a severe hemophilia A genotype; 4) Studies of the immune response to FVIII in severe hemophilia A; 5) Development of a well-curated annotated data set of genetic, hemophilia, immune, environmental, psychosocial, and quality of life metrics; 6) Development of a multi-omics and immunologic biospecimen resource; and 7) Development of the hemophilia analytical Portal (F8portal.org).

Study design: The HARP is a multicenter and decentralized prospective observational longitudinal cohort study beginning in pregnancy. It will follow 50 mother-baby pairs where the babies have severe hemophilia A and the mothers have a severe hemophilia A genotype. The private Clinical Consortium (CC) will oversee the study throughout the U.S., including sites that care for the mothers (up to 200 sites) and sites that care for the child (up to 70 sites). The CC will also conduct decentralized aspects of the study including collection of patient reported outcomes and local sample collection.

The primary maternal endpoint is primary postpartum hemorrhage; the primary pediatric endpoint is rate of development of humoral immune response to FVIII and proportion that progress to clinical inhibitors. Mother and child secondary endpoints reflect the diverse research the HARP resource will support.

Inclusion criteria for the pregnant person are: Pregnant and prior to 37 weeks gestation, known or at-risk to have a severe hemophilia A genotype, pregnant with a fetus at-risk for severe hemophilia A, ability to give informed consent, and > 18 years old. Inclusion criteria for the child are: severe hemophilia A, born to a person in the study.

Exclusion/discontinuation criteria are: Presence of another significant bleeding disorder in mother or child; mother age <18 years; no fetus is at-risk to inherit severe hemophilia A; the child does not have severe hemophilia A; the child has a severe immune disorder; the mother or child participates in another study with blood collection volumes that exceed safety limits; mother's or child's healthcare will be outside the U.S.; the mother is a prisoner; any other reason that in the opinion of the investigator a subject is unsuitable for the study

Summary: The HARP innovates in multiple areas of clinical study design to conduct a national prospective longitudinal intergenerational study in a rare disorder beginning in pregnancy. The structure includes a new multidisciplinary CC, systematic inclusion of Lived Experience Experts, strategies for broad community engagement, recruitment, and retention, and decentralized operations. This cohort will enable deep characterization, including genomics and other -omics, on pregnancy-associated bleeding and drivers of FVIII inhibitors in hemophilia A. The HARP Shareable Resource will be comprised of well annotated data and biological samples accessible to researchers through a portal, F8portal.org, and a linked biorepository.